Optimal Effect of Lactobacillus delbruecki subsp. bulgaricus, Among Other Lactobacilli Species, on the Number of IgA and Mast Cells Associated with the Mucosa in Immunosuppressed Mice

In previous papers we demonstrated the influence of the oral administration of different lactic acid bacteria on the systemic immune response and the protective effect against an infection with Candida albicans in a corticoid immunosuppressed experimental model in mice. The gastrointestinal and respiratory tracts are the most common sites of entry of the infectious agents at the mucosal surfaces. The IgA secreting cells and mastocytes play an important role in host defence against pathogens. The aim of this study was to determine whether or not some lactobacilli strains have influence on the number of IgA and mast cells associated with the gut and bronchus mucosa, in mice immunosuppressed by corticoid therapy. Groups of animals were immunosuppressed by corticoid oral administration (50 mg kg-1). They were split into four experimental groups: immunosuppressed control mice and the immunosuppressed test groups, which were given L. casei, L. delbruecki subsp. bulgaricus or L. acidophilus at a concentration of 1 X 109 cells/day/mouse, on days 8 and 9 post-corticoid. We demonstrated that the lactobacilli strains assayed were able to increase the number of IgA secreting cells and mast cells associated with both gut and bronchus mucosa, the effect being more remarkable for L. delbruecki subsp. bulgaricus. The enhancement of the IgA secreting cells and mast cells, in an immunosuppressed host induced by lactobacilli administration specially by L. delbruecki subsp. bulgaricus, suggest the potential of its use as adjuvant therapy to protect mucosal surfaces.